These types of cruise control systems make it possible to set the vehicle's speed to an intended speed selected by the driver. Since the sensor device also incorporates a distance sensor, for example in the form of a radar sensor, a stereo camera system or the like, the vehicle speed may also be set in such a way that a suitable safety distance to a vehicle ahead is automatically maintained. An example of such a control system, which is also known as an ACC (Active Cruise Control) system, is described in “Adaptive Cruise Control Systems—Aspects and Development Trends,” by Winner, Witte, Uhler and Lichtenberg, Robert Bosch GmbH, in SAE Technical Papers Series 961010, International Congress and Exposition, Detroit, Feb. 26-29, 1996.
However, since the available sensor devices do not yet permit complete coverage and safe evaluation of the traffic environment, to date such systems have been primarily suitable for relatively stable traffic situations, such as driving on a highway or expressway. In urban traffic or when driving at low speeds on winding roads, however, uncertainties in detecting the particular relevant target object could create a risk of an accident. For this reason, known ACC systems are designed in such a way that they are activatable only above a certain threshold speed.
However, it has been proposed to expand the application range of the ACC system to a traffic situation described as stop-and-go, which occurs, for example, in a traffic jam or in slow-moving traffic. This traffic situation, too, is relatively stable and is therefore suitable for automatic distance control. However, the functionality must be expanded in such a way that stopping and going may also be controlled or regulated automatically.
In addition, the application range of this stop-and-go function should be limited to speeds below a certain value; the speed ranges for the ACC function and the stop-and-go function may overlap.
However, an accident risk may occur under certain circumstances, even at low speed, in the event of the driver relying on the automatic function of the cruise control system in an inappropriate situation, in particular when the driver also uses the stop-and-go function improperly in urban traffic while turning or in residential areas.